Stobart Air is adding two new routes to the Aer Lingus Regional network, which it operates.
A new Dublin to Cardiff route will initially operate three times a week from August 30.
The service will be available on Monday, Friday and Sunday.
Flights between Belfast and Cardiff will initially operate four times a week - on Monday, Friday, Saturday and Sunday - from August 30.
Stobart Air said its flights operate in line with protocols put in place by the UK and Irish governments and health authorities.
It has called on the Government here to outline a roadmap for the safe resumption of air travel, and to put in place a vaccine passport policy to allow people who have received a complete dose of the Covid-19 vaccine to travel within the Ireland-UK Common Travel area.
"Airlines need to be able to plan and resource their schedules in advance, so it is critical that the government can outline a roadmap for the resumption of international travel," Andy Jolly, Managing Director at Stobart Air said.
A deal to sell Stobart Air to the Isle of Man based company, Ettyl, was announced last month.
According to Esken - formerly known as the Stobart Group - the deal is expected to be completed this month.